1820.] Mr. Booth on the Cornea of the Eye. 31 



inunicated by the layers of the cornea to the particles of aqueous 

 fluid contauied between them ; or by a mutual action upon each 

 other, I am at present unable to say. But the fact is evident 

 that if pressure be applied to a cornea containing aqueous 

 humour between its layers, a pecuhar polar arrano-enient takes 

 place producing perfect opacity. I should not ^suppose any 

 change to have taken place in the nature of the cornea • for 

 even in the fresh eye, the effect may be produced, bv applying; a 

 remitted pressure for a short time— pumping, as it were the 

 fluid into the layers of the cornea. If the tunica conjunctiva be 

 removed, tne fluid will be seen exuding from the surface in the 

 form of dew, and the eftect gradually takes place. It is more 

 obvious when the conjunctiva is not removed, on account of its 

 being a more impervious membrane, and by ofl'ering a resistance 

 to the passage of the humour allows a greater accumulation of it 

 between the layers of the cornea. When all the layers are 

 removed except the last, the whole structure upon which the 

 phenomenon depended becomes destroyed ; for in this case the 

 flmd having only one layer to pass through, it escapes without 

 any degree of pressure, and without producing any eftect • 

 whereas when more than one layer exist, the fluid becomes 

 entangled between them, and in this situation is aflfected by the 

 pressure from behind. 



In Mr. Wardrop's Anatomy of the Eve, he mentions a case of 

 opacity resulting from a larger secretion of aqueous fluid than 

 usual ; and being induced to puncture the cornea to allow some 

 of It to escape, he found the transparency instantly restored. 

 Ihe opacity, in this mstance, most likely depended upon some 

 morbid peculiarity of the cornea, communicated to it by the 

 disease existing in the contiguous membrane of the aqueous 

 humour and which had primarily produced an increase of that 

 fluid, ihis morbid pecuharity allowing of a transudation of the 

 fluid between its coats, which, being acted upon by the pressure 

 trom the mcreased quantity of aqueous fluid, produced the 

 opacity. 1 his case Avould appear to depend more upon the 

 morbid state of the cornea than the pressure ; for we have often 

 an increase in the quantity of aqueous fluid in the anterior 

 Chamber of the eye, producing pressure, but not opacity. 



±5y causing various fluids to pass between the layers of the 

 membrane, I was in hopes of arriving at a more cer'tain know- 

 ledge of the nature of this polarity; my results, from the imper- 

 fect manner in which my experiments were performed, were too 

 various to place much confidence in them. As I intend pursuing 

 the subject, should I be able to arrive at any thing determinate, 

 1 may again obtrude myself upon the pages of yom- journal. 

 I am. Sir, your most obedient servant, 



Thomas S. Booth. 



